Measurement Computing USB-TEMP User Manual

USB-TEMP

Measurement Advantage™ brand

USB-based High-Precision 8-Channel

Temperature Measurement Module

User's Guide

© Copyright 2005, Measurement Computing Corporation

Document Revision 2, March, 2005

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Refer to www.mccdaq.com/execteam.html for the names, titles, and contact information of each key executive at
Measurement Computing.

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USB-TEMP User's Guide

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HM PMD-Temp.doc

ii

Table of Contents

Preface

About this User’s Guide .......................................................................................................................v

What you will learn from this user’s guide.........................................................................................................v

Conventions in this user’s guide.........................................................................................................................v

Where to find more information.........................................................................................................................v

Chapter 1

Introducing the USB-TEMP .............................................................................................................. 1-1

Overview: USB-TEMP features..................................................................................................................... 1-1

USB-TEMP block diagram............................................................................................................................. 1-2

Software features............................................................................................................................................ 1-2

Connecting a USB-TEMP to your computer is easy ...................................................................................... 1-3

Chapter 2

Installing the USB-TEMP .................................................................................................................. 2-1

What comes with your USB-TEMP shipment? .............................................................................................. 2-1

Hardware ....................................................................................................................................................................... 2-1

Software......................................................................................................................................................................... 2-1

Documentation............................................................................................................................................................... 2-2

Unpacking the USB-TEMP ............................................................................................................................ 2-2

Installing the software .................................................................................................................................... 2-2

Installing the hardware ................................................................................................................................... 2-2

Configuring the USB-TEMP .......................................................................................................................... 2-3

Calibrating the USB-TEMP............................................................................................................................ 2-3

Chapter 3

Sensor Connections ......................................................................................................................... 3-1

Screw terminal pin out.................................................................................................................................... 3-1

Sensor input terminals (C0H/C0L to C7H/C7L)............................................................................................................ 3-2

Current excitation output terminals (±I1 to ±I4) ............................................................................................................ 3-2

Four-wire, two sensor common terminals (4W01 to 4W67).......................................................................................... 3-3

Two sensor common terminals (IC01 to IC67).............................................................................................................. 3-3

Ground terminals (GND) ............................................................................................................................................... 3-3

Power terminals (+5V)................................................................................................................................................... 3-3

Digital terminals (DIO0 to DIO7).................................................................................................................................. 3-3

CJC sensors.................................................................................................................................................................... 3-3

Thermocouple connections............................................................................................................................. 3-3

Wiring configuration...................................................................................................................................................... 3-3

RTD and thermistor connections.................................................................................................................... 3-4

Two-wire configuration ................................................................................................................................................. 3-4

Three-wire configuration ............................................................................................................................................... 3-5

Four-wire configuration................................................................................................................................................. 3-6

Semiconductor sensor measurements ............................................................................................................. 3-7

Wiring configuration...................................................................................................................................................... 3-7

Digital I/O connections................................................................................................................................... 3-7

Chapter 4

Functional Details ............................................................................................................................. 4-1

Thermocouple measurements ......................................................................................................................... 4-1

Cold junction compensation (CJC)................................................................................................................................ 4-1

Data linearization........................................................................................................................................................... 4-1

Open-thermocouple detection (OTD) ............................................................................................................................ 4-1

RTD and thermistor measurements ................................................................................................................ 4-2

iii

USB-TEMP User's Guide

Data linearization........................................................................................................................................................... 4-2

USB connector ............................................................................................................................................... 4-2

LED ................................................................................................................................................................ 4-2

Power.............................................................................................................................................................. 4-2

Chapter 5

Specifications ....................................................................................................................................5-1

Analog input section....................................................................................................................................... 5-1

Channel configurations................................................................................................................................... 5-2

Compatible sensors......................................................................................................................................... 5-2

Accuracy......................................................................................................................................................... 5-3

Thermocouple measurement accuracy........................................................................................................................... 5-3

Semiconductor sensor measurement accuracy............................................................................................................... 5-3

RTD measurement accuracy .......................................................................................................................................... 5-4

Thermistor measurement accuracy.................................................................................................................................5-4

Throughput rate .............................................................................................................................................. 5-5

Digital input/output ........................................................................................................................................ 5-6

Memory .......................................................................................................................................................... 5-6

Microcontroller............................................................................................................................................... 5-6

USB +5V voltage ........................................................................................................................................... 5-6

Power.............................................................................................................................................................. 5-7

USB specifications ......................................................................................................................................... 5-7

Current excitation outputs (Ix+) ..................................................................................................................... 5-7

Environmental ................................................................................................................................................ 5-8

Mechanical ..................................................................................................................................................... 5-8

Screw terminal connector type and pin out .................................................................................................... 5-8

Screw terminal pin out................................................................................................................................................... 5-9

iv

Preface

About this User’s Guide

What you will learn from this user’s guide

This user’s guide explains how to install, configure, and use the USB-TEMP so that you get the most out
of its USB-based temperature measurement features.

This user’s guide also refers you to related documents available on our web site, and to technical support
resources that can also help you get the most out of these boards.

Conventions in this user’s guide

For more information on …

Text presented in a box signifies additional information and helpful hints related to the subject matter you
are reading.

Caution! Shaded caution statements present information to help you avoid injuring yourself and

others, damaging your hardware, or losing your data.

<#:#>

bold text Bold indicates names of objects on the screen, such as buttons, text boxes, and check boxes. For

italic text

Angle brackets that enclose numbers separated by a colon signify a range of numbers, such as
those assigned to registers, bit settings, etc.

example:

1. Insert the disk or CD and click the OK button.

Italic text indicates the names of manuals and help topic titles, and to emphasize a word or
phrase. For example:

! The InstaCal® installation procedure is explained in the DAQ Software Quick Start.
! Never touch the exposed pins or circuit connections on the board.

Where to find more information

The following electronic documents provide helpful information relevant to the operation of the USB­TEMP.

! MCC's Specifications: USB-TEMP (the PDF version of Chapter 5 in this guide) is available on our

web site at www.mccdaq.com/pdfs/USB-TEMP.pdf

! MCC's DAQ Software Quick Start is available on our web site at

! MCC's Guide to Signal Connections is available on our web site at

www.mccdaq.com/signals/signals.pdf

! MCC's Universal Library User's Guide is available on our web site at

! MCC's Universal Library Function Reference is available on our web site at

! MCC's Universal Library for LabVIEW

.

™

User’s Guide is available on our web site at

.

.

.

.

.

.

v

Chapter 1

Introducing the USB-TEMP

Overview: USB-TEMP features

This user's guide contains all of the information you need to connect the USB-TEMP to your computer
and to the signals you want to measure. The USB-TEMP is part of the Measurement Advantage™ brand
of USB-based data acquisition products.

The USB-TEMP is a USB 2.0 full-speed, temperature measurement module that is supported under
Microsoft
TEMP is fully compatible with both USB 1.1 and USB 2.0 ports.

The USB-TEMP provides eight differential input channels that are software programmable for different
sensor categories including thermocouple, RTD’s, thermistors and Semiconductor sensors. Eight
independent, TTL-compatible digital I/O channels are provided to monitor TTL-level inputs,
communicate with external devices, and to generate alarms. The digital I/O channels are software
programmable for input or output.

With the USB-TEMP, you can take measurements from four sensor categories:

! Thermocouple – types J, K, R, S, T, N, E, and B
! Resistance temperature detectors (RTDs) – 2, 3, or 4-wire measurements of 100 Ω platinum RTDs
! Thermistors – 2, 3, or 4-wire measurements
! Semiconductor temperature sensors – LM36 or equivalent

The USB-TEMP provides a 24-bit analog-to-digital (A/D) converter for each pair of differential analog
input channels. Each pair of differential inputs constitutes a channel pair.

You can connect a different category of sensor to each channel pair, but you can not mix categories
among the channels that constitute a channel pair (although it is permissible to mix thermocouple types).

The USB-TEMP provides two integrated cold junction compensation (CJC) sensors for thermocouple
measurements, and built-in current excitation sources for resistive sensor measurements.

An open thermocouple detection feature lets you detect a broken thermocouple. An on-board
microprocessor automatically linearizes the measurement data according to the sensor category.

®

Windows® 98 (2nd edition), Windows ME, Windows 2000, and Windows XP. The USB-

The USB-TEMP is a standalone plug-and-play module which draws power from the USB cable. No
external power supply is required. All configurable options are software programmable.

The USB-TEMP is fully software calibrated.

1-1

USB-TEMP User's Guide Introducing the USB-TEMP

USB-TEMP block diagram

USB-TEMP functions are illustrated in the block diagram shown here.

Precision

5V Ref.

DIO

±

Ix

USB

USB

Micro

USB

+5V

I/O

Isolator

Isolated

DC/DC

500 V

Isolation

Barrier

8

Isolated

Micro

Te mp

sensor

(+12)

(-12)

Figure 1-1. USB-TEMP functional block diagram

SPI

24-bit A/D

(CH0, CH1)

24-bit A/D

(CH2, CH3)

24-bit A/D

(CH4, CH5)

24-bit A/D

(CH6, CH7)

Input
mux.

±

Ix

Input
mux.

CJC

CH0-3

±

Ix

Input
mux.

±

Ix

Input
mux.

CJC

CH4-7

Screw terminalScrew terminalScrew terminal

Software features

The following software ships with the USB-TEMP free of charge.

! InstaCal installation, calibration, and test utility
! TracerDAQ™ suite of virtual instruments
! SoftWIRE® for Visual Studio® .NET graphical programming
! MCC DAQ Components for VS .NET (installed with SoftWIRE for VS .NET)

For information on the features of InstaCal, TracerDAQ, and SoftWIRE, refer to the DAQ Software
Quick Start booklet that shipped with the USB-TEMP.

1-2

USB-TEMP User's Guide Introducing the USB-TEMP

Connecting a USB-TEMP to your computer is easy

Installing a data acquisition device has never been easier.

! The USB-TEMP relies upon the Microsoft Human Interface Device (HID) class drivers. The HID

class drivers ship with every copy of Windows that is designed to work with USB ports. We use the
Microsoft HID because it is a standard, and its performance delivers full control and maximizes data
transfer rates for your USB-TEMP. No third-party device driver is required.

! The USB-TEMP is plug-and-play. There are no jumpers to position, DIP switches to set, or interrupts

to configure.

! You can connect the USB-TEMP before or after you install the software, and without powering

down your computer first. When you connect an HID to your system, your computer automatically
detects it and configures the necessary software. You can connect and power multiple HID
peripherals to your system using a USB hub.

! You can connect your system to various devices using a standard four-wire cable. The USB

connector replaces the serial and parallel port connectors with one standardized plug and port
combination.

! You do not need a separate power supply module. The USB automatically delivers the electrical

power required by each peripheral connected to your system.

! Data can flow two ways between a computer and peripheral over USB connections.

1-3

Installing the USB-TEMP

What comes with your USB-TEMP shipment?

The following items are shipped with the USB-TEMP.

Hardware

The following items should be included with your shipment.

! USB-TEMP

Chapter 2

! USB cable (2 meter length)

Software

The Measurement Computing Data Acquisition Software CD contains the following software:

! InstaCal installation, calibration, and test utility
! TracerDAQ suite of virtual instruments
! SoftWIRE for VS .NET
! SoftWIRE MCC DAQ Components for .NET

(installed with SoftWIRE for VS .NET)

2-1

USB-TEMP User's Guide Installing the USB-TEMP

Documentation

Unpacking the USB-TEMP

As with any electronic device, you should take care while handling to avoid damage from static
electricity. Before removing the USB-TEMP from its packaging, ground yourself using a wrist strap or by
simply touching the computer chassis or other grounded object to eliminate any stored static charge.

If your USB-TEMP is damaged, notify Measurement Computing Corporation immediately by phone, fax,
or e-mail. For international customers, contact your local distributor where you purchased the USB­TEMP.

! Phone: [phone] and follow the instructions for reaching Tech Support.
! Fax: [phone] to the attention of Tech Support
! Email: [e-mail]

Installing the software

Refer to the DAQ Software Quick Start for instructions on installing the software on the Measurement
Computing Data Acquisition Software CD. This booklet is available in PDF at

Installing the hardware

To connect the USB-TEMP to your system, turn your computer on, and connect the USB cable to a USB
port on your computer or to an external USB hub that is connected to your computer. The USB cable
provides power and communication to the USB-TEMP.

When you connect the USB-TEMP for the first time, a
XP) or dialog (other Windows versions) opens as the USB-TEMP is detected.

When this balloon or dialog closes, the installation is complete. The USB LED should flash and then
remain lit. This indicates that communication is established between the USB-TEMP and your computer.

Found New Hardware popup balloon (Windows

Caution! Do not disconnect any device from the USB bus while the computer is communicating with

the USB-TEMP, or you may lose data and/or your ability to communicate with the USB­TEMP.

2-2

USB-TEMP User's Guide Installing the USB-TEMP

If the LED turns off

If the LED is lit but then turns off, the computer has lost communication with the USB-TEMP. To restore
communication, disconnect the USB cable from the computer, and then reconnect it. This should restore
communication, and the LED should turn back on.

Configuring the USB-TEMP

All hardware configuration options on the USB-TEMP are programmable with software. Use InstaCal to
set the sensor type for each channel. The configurable options dynamically update according to the
selected sensor category. Configuration options are stored on the USB-TEMP 's isolated microcontroller
in EEPROM, which is non-volatile memory on the USB-TEMP module. Configuration options are loaded
on power up.

Default configuration

The factory default configuration is Disabled. The Disabled mode disconnects the analog inputs from the
terminal blocks and internally grounds all of the A/D inputs. This mode also disables each of the current
excitation sources.

Warm up

Allow the USB-TEMP to warm up for 30 minutes before taking measurements. This warm up time
minimizes thermal drift and achieves the specified rated accuracy of measurements.

For RTD or thermistor measurements, this warm-up time is also required to stabilize the internal current
reference.

Calibrating the USB-TEMP

The USB-TEMP is fully calibrated via software. InstaCal prompts you to run its calibration utility when
you change from one sensor category to another.

Allow the USB-TEMP to operate for at least 30 minutes before calibrating. This warm up time minimizes
thermal drift and achieves the specified rated accuracy of measurements.

2-3

Chapter 3

Sensor Connections

The USB-TEMP supports the following temperature sensor types:

! Thermocouple – types J, K, R, S, T, N, E, and B
! Resistance temperature detectors (RTDs) – 2, 3, or 4-wire measurement modes of 100 Ω platinum

RTDs.

! Thermistors – 2, 3, or 4-wire measurement modes.
! Semiconductor temperature sensors – LM36 or equivalent

Sensor selection

The type of sensor you select will depend on your application needs. Review the temperature ranges and
accuracies of each sensor type to determine which is best suited for your application.

Screw terminal pin out

The USB-TEMP has four rows of screw terminals — two rows on the top edge of the housing, and two
rows on the bottom edge. Each row has 26 connections. Between each bank of screw terminals are two
integrated CJC sensors used for thermocouple measurements. Signals are identified in Figure 3-1.

27 I4-

28 GND

29 C7L

30 C7H

31 IC67

32 4W67

33 C6L

34 C6H

35 NC

36 I4+

37 I3-

CJC SensorCJC Sensor

38 GND

39 C5L

40 C5H

41 IC45

42 4W45

43 C4L

44 C4H

45 NC

46 I3+

47 +5V

48 GND

49 DIO7

50 DIO6

51 DIO5

52 DIO4

I1+ 1

NC 2

C0H 3

C0L 4

Figure 3-1. USB-TEMP screw terminal pin numbers

4W01 5

IC01 6

C1H 7

C1L 8

GND 9

I1- 10

I2+ 11

NC 12

C2H 13

C2L 14

4W23 15

IC23 16

C3H 17

C3L 18

GND 19

I2- 20

+5V 21

GND 22

DIO0 23

DIO1 24

DIO2 25

DIO3 26

3-1

USB-TEMP User's Guide Sensor Connections

Table 3-1. USB-TEMP screw terminal descriptions

Pin Signal

Name

1 I1+ CH0/CH1 current excitation source 27 I4- CH6/CH7 current excitation return
2 NC Not connected 28 GND Ground
3 C0H CH0 sensor input (+) 29 C7L

4 C0L

5 4W01 CH0/CH1 4-wire, 2 sensor common 31 IC67 CH6/CH7 2 sensor common
6 IC01 CH0/CH1 2-sensor common 32 4W67 CH6/CH7 4-wire, 2 sensor common
7 C1H CH1 sensor input (+) 33 C6L

8 C1L

9 GND Ground 35 NC Not connected
10 I1- CH0/CH1 current excitation return 36 I4+ CH6/CH7 current excitation source

CJC sensor

11 I2+ CH2/CH3 current excitation source 37 I3- CH4/CH5 current excitation return
12 NC Not connected 38 GND Ground
13 C2H CH2 sensor input (+) 39 C5L

14 C2L

15 4W23 CH2/CH3 4-wire, 2 sensor common 41 IC45 CH4/CH5 2 sensor common
16 IC23 CH2/CH3 2 sensor common 42 4W45 CH4/CH5 4-wire, 2 sensor common
17 C3H CH3 sensor input (+) 43 C4L

18 C3L

19 GND Ground 45 NC Not connected
20 I2- CH2/CH3 current excitation return 46 I3+ CH4/CH5 current excitation source
21 +5V +5V output 47 +5V +5V output
22 GND Ground 48 GND Ground
23 DIO0 Digital Input/Output 49 DIO7 Digital Input/Output
24 DIO1 Digital Input/Output 50 DIO6 Digital Input/Output
25 DIO2 Digital Input/Output 51 DIO5 Digital Input/Output
26 DIO3 Digital Input/Output 52 DIO4 Digital Input/Output

Pin Description Pin Signal

CH0 sensor input (

CH1 sensor input (

CH2 sensor input (

CH3 sensor input (

-)

-)

-)

-)

Name

30 C7H CH7 sensor input (+)

34 C6H CH6 sensor input (+)

CJC sensor

40 C5H CH5 sensor input (+)

44 C4H CH4 sensor input (+)

Pin Description

CH7 sensor input (

CH6 sensor input (

CH5 sensor input (

CH4 sensor input (

-)

-)

-)

-)

Use 16 AWG to 30 AWG wire for your signal connections.

Tighten screw terminal connections

When making connections to the screw terminals, be sure to tighten the screw until tight. Simply
touching the top of the screw terminal is not sufficient to make a proper connection.

Sensor input terminals (C0H/C0L to C7H/C7L)

You can connect up to eight temperature sensors to the differential sensor inputs (C0H/C0L to
C7H/C7L). Supported sensor categories include thermocouples, RTDs, thermistors, or semiconductor
sensors.

Do not mix sensor categories within channel pairs. It is permitted to mix thermocouple types (J, K, R, S,
T, N, E, and B) within channel pairs, however.

Do not connect two different sensor categories to the same channel pair

The USB-TEMP provides a 24 bit A/D converter for each channel pair. Each channel pair can monitor
one sensor category. To monitor a sensor from a different category, connect the sensor to a different
channel pair (input terminals).

Current excitation output terminals (±I1 to ±I4)

The USB-TEMP has four dedicated pairs of current excitation output terminals (±I1 to ±I4). These
terminals have a built-in precision current source to provide excitation for the resistive sensors used for
RTD and thermistor measurements.

3-2

USB-TEMP User's Guide Sensor Connections

Each current excitation terminal is dedicated to one pair of sensor input channels:

! I1+ is the current excitation source for channel 0 and channel 1
! I2+ is the current excitation source for channel 2 and channel 2
! I3+ is the current excitation source for channel 4 and channel 5
! I4+ is the current excitation source for channel 6 and channel 7

Four-wire, two sensor common terminals (4W01 to 4W67)

These terminals are used as the common connection for four-wire configurations with two RTD or
thermistor sensors.

Two sensor common terminals (IC01 to IC67)

These terminals are used as the common connection for two-wire configurations with two RTD or
thermistor sensors.

Ground terminals (GND)

The six ground terminals (GND) provide a common ground for the input channels and DIO bits and are
isolated (500 VDC) from the USB GND.

Power terminals (+5V)

The two +5V output terminals are isolated (500 VDC) from the USB +5V.

Digital terminals (DIO0 to DIO7)

You can connect up to eight digital I/O lines to the screw terminals labeled DIO0 to DIO7. Each terminal
is software configurable for input or output.

CJC sensors

The USB-TEMP has two built in high-resolution temperature sensors. One sensor is located on the right
side of the package, and one sensor is located at the left side.

Thermocouple connections

A thermocouple consists of two dissimilar metals that are joined together at one end. When the junction
of the metals is heated or cooled, a voltage is produced that correlates to temperature.

The USB-TEMP makes fully differential thermocouple measurements without the need of ground­referencing resistors. A 32-bit floating point value in either a voltage or temperature format is returned by
software. An open thermocouple detection feature is available for each analog input which automatically
detects an open or broken thermocouple.

Use InstaCal to select the thermocouple type (J, K, R, S, N. E, and B) and one or more sensor input
channels to connect the thermocouple.

Wiring configuration

Connect the thermocouple to the USB-TEMP using a differential configuration, as shown in Figure 3-2.

I#+NCC#H

Figure 3-2. Typical thermocouple connection

C#L

4W##

IC##

C#H

C#L

GND

I#-

3-3

USB-TEMP User's Guide Sensor Connections

The USB-TEMP GND pins are isolated from earth ground, so connecting thermocouple sensors to
voltages referenced to earth ground is permissible as long as the isolation between the GND pins (9, 19,
28, 38) and earth ground is maintained.

When thermocouples are attached to conductive surfaces, the voltage differential between multiple
thermocouples must remain within ±1.4 V. For best results, we recommend the use of insulated or
ungrounded thermocouples when possible.

Maximum input voltage between analog input and ground

The absolute maximum input voltage between an analog input and the isolated GND pins is ±25 VDC
when the USB-TEMP is powered on, and ±40 VDC when the USB-TEMP is powered off.

If you need to increase the length of your thermocouple, use the same type of thermocouple wires to
minimize the error introduced by thermal EMFs.

RTD and thermistor connections

A resistance temperature detector (RTD) measures temperature by correlating the resistance of the RTD
element with temperature. A thermistor is a thermally-sensitive resistor that is similar to an RTD in that
its resistance changes with temperature — thermistors show a large change in resistance that is
proportional to a small change in temperature. The main difference between RTD and thermistor
measurements is the method used to linearize the sensor data.

RTDs and thermistors are resistive devices that require an excitation current to produce a voltage drop
that can be measured differentially across the sensor. The USB-TEMP features four built-in current
excitation sources (±I1 to ±I4) for measuring resistive type sensors. Each current excitation terminal is
dedicated to one channel pair.

The USB-TEMP makes two, three, and four-wire measurements of RTD’s (100 Ω platinum type) and
thermistors.

Use InstaCal to select the sensor type and the wiring configuration. Once the resistance value is
calculated, the value is linearized in order to convert it to a temperature value. A 32-bit floating point
value in either temperature or resistance is returned by software.

RTD maximum resistance

Resistance values greater than 660 Ω cannot be measured by the USB-TEMP in the RTD mode. The
660 Ω resistance limit includes the total resistance across the current excitation (±Ix) pins, which is the
sum of the RTD resistance and the lead resistances.

Thermistor maximum resistance

Resistance values greater than 180k ohms cannot be measured by the USB-TEMP in the thermistor mode.
The 180 k Ω resistance limit includes the total resistance across the current excitation (±Ix) pins, which is
the sum of the thermistor resistance and the lead resistance.

Two-wire configuration

The easiest way to connect an RTD sensor or thermistor to the USB-TEMP is with a two-wire
configuration, since it requires the fewest connections to the sensor. With this method, the two wires that
provide the RTD sensor with its excitation current also measure the voltage across the sensor.

Since RTDs exhibit a low nominal resistance, measurement accuracy can be affected due to the lead wire
resistance. For example, connecting lead wires that have a resistance of 1 Ω (0.5 Ω each lead) to a 100 Ω
platinum RTD will result in a 1% measurement error.

With a two-wire configuration, you can connect either one sensor per channel pair, or two sensors per
channel pair.

3-4

USB-TEMP User's Guide Sensor Connections

Two-wire, single-sensor

A two-wire single-sensor measurement configuration is shown in Figure 3-3.

I#+

NC

C#H

C#L

Figure 3-3. Two-wire, single RTD or thermistor sensor measurement configuration

When you select a two-wire single sensor configuration with InstaCal, connections to C#H and C#L are
made internally.

Two-wire, two sensor

A two-wire, two-sensor measurement configuration is shown in Figure 3-4.

I#+

NC

C#H

C#L

Figure 3-4. Two-wire, two RTD or thermistor sensors measurement configuration

C#H

4W##

IC##

C#L

GND

I#-

4W##

IC##

C#H

C#L

GND

I#-

When you select a two-wire, two sensor configuration with InstaCal, connections to C#H (first sensor)
and C#H/C#L (second sensor) are made internally.

When configured for two-wire mode, both sensors must be connected to obtain proper measurements.

Three-wire configuration

A three-wire configuration compensates for lead-wire resistance by using a single voltage sense
connection. With a three-wire configuration, you can connect only one sensor per channel pair. A
three-wire measurement configuration is shown in Figure 3-5.

I#+

NC

C#H

C#L

4W##

IC##

C#H

C#L

GND

I#-

Figure 3-5. Three-wire RTD or thermistor sensor measurement configuration

When you select a three-wire sensor configuration with InstaCal, the USB-TEMP measures the lead
resistance on the first channel (C#H/C#L) and measures the sensor itself using the second channel
(C#H/C#L). This configuration compensates for any lead-wire resistance and temperature change in lead­wire resistance. Connections to C#H for the first channel and C#H/C#L of the second channel are made
internally.

3-5

USB-TEMP User's Guide Sensor Connections

Three-wire compensation

For accurate three wire compensation, the individual lead resistances connected to the ±I# pins must be of
equal resistance value.

Four-wire configuration

With a four-wire configuration, connect two sets of sense/excitation wires at each end of the RTD or
thermistor sensor. This configuration completely compensates for any lead-wire resistance and
temperature change in lead-wire resistance.

Connect your sensor with a four-wire configuration when your application requires very high accuracy
measurements. Examples of a four-wire single-sensor measurement configuration are shown in Figure
3-6 and Figure 3-7.

You can configure the USB-TEMP with either a single sensor per channel or two sensors per channel
pair.

Four-wire, single-sensor

A four-wire, single-sensor connected to the first channel of a channel pair is shown in Figure 3-6.

I#+

NC

C#H

C#L

4W##

IC##

C#H

C#L

GND

I#-

Figure 3-6. Four-wire, single RTD or thermistor sensor measurement configuration

A four-wire, single-sensor connected to the second channel of a channel pair is shown in Figure 3-7.

I#+

NC

C#H

C#L

4W##

IC##

C#H

C#L

GND

I#-

Figure 3-7. Four-wire, single RTD or thermistor sensor measurement configuration

A four-wire, two-sensor measurement configuration is shown in Figure 3-8.

I#+NCC#H

C#L

4W##

C#H

C#L

GND

I#-

Figure 3-8. Four-wire, two RTD or thermistor sensors measurement configuration

When configured for two-wire mode, both sensors must be connected to obtain proper measurements.

3-6

USB-TEMP User's Guide Sensor Connections

Semiconductor sensor measurements

Semiconductor sensors are suitable over a range of approximately -40 °C to 125 °C, where an accuracy of
±2 °C is adequate. The temperature measurement range of a semiconductor sensor is small when
compared to thermocouples and RTDs. However, semiconductor sensors can be accurate, inexpensive
and easy to interface with other electronics for display and control.

The USB-TEMP makes high-resolution measurements of semiconductor sensors, such as the LM36 or
equivalent, and returns a 32-bit floating point value in either a voltage or temperature format.

Use InstaCal to select the sensor type (TMP36 or equivalent) and the sensor input channel to connect the
sensor.

Wiring configuration

You can connect a TMP36 (or equivalent) semiconductor sensor to the USB-TEMP using a single-ended
configuration, as shown in Figure 3-9. The USB-TEMP also provides
the sensor.

+5V and GND pins for powering

I#+NCC#H

5V

Figure 3-9. Semiconductor sensor measurement configuration

The software outputs the measurement data as a 32-bit floating point value in either voltage or
temperature.

TMP36

C#L

4W##

IC##

C#H

C#L

GND

I#-

Digital I/O connections

You can connect up to eight digital I/O lines to the screw terminals labeled DIO0 to DIO7. You can
configure each digital bit for either input or output. All digital I/O lines are pulled up to +5V with a
47 K ohm resistor (default). You can request the factory to configure the resistor for pull-down to ground
if desired.

When you configure the digital bits for input, you can use the USB-TEMP digital I/O terminals to detect
the state of any TTL-level input. Refer to the schematic shown in Figure 3-10. If you set the switch to the
+5V input, DIO0 reads TRUE (1). If you move the switch to GND, DIO0 reads FALSE (0).

DIO0

Figure 3-10. Schematic showing switch detection by digital channel DIO0

Caution! All ground pins on the USB-TEMP (pins 9, 19, 28, 38) are common and are isolated from

earth ground. If a connection is made to earth ground when using digital I/O and conductive
thermocouples, the thermocouples are no longer isolated. In this case, thermocouples must
not be connected to any conductive surfaces that may be referenced to earth ground.

For general information regarding digital signal connections and digital I/O techniques, refer to the Guide
to Signal Connections (available on our web site at www.mccdaq.com/signals/signals.pdf

+5V+GND

3-7

).

Chapter 4

Functional Details

Thermocouple measurements

A thermocouple consists of two dissimilar metals that are joined together at one end. When the junction
of the metals is heated or cooled, a voltage is produced that correlates to temperature.

The USB-TEMP hardware level-shifts the thermocouple’s output voltage into the A/D’s common mode
input range by applying +2.5 V to the thermocouple’s low side at the C#L input. Always connect
thermocouple sensors to the USB-TEMP in a floating fashion. Do not attempt to connect the
thermocouple low side C#L to GND or to a ground referencing resistor.

Cold junction compensation (CJC)

When you connect the thermocouple sensor leads to the sensor input channel, the dissimilar metals at the
USB-TEMP terminal blocks produce an additional thermocouple junction. This junction creates a small
voltage error term which must be removed from the overall sensor measurement using a cold junction
compensation technique. The measured voltage includes both the thermocouple voltage and the cold
junction voltage. To compensate for the additional cold junction voltage, the USB-TEMP subtracts the
cold junction voltage from the thermocouple voltage.

The USB-TEMP has two high-resolution temperature sensors that are integrated into the design of the
USB-TEMP. One sensor is located on the right side of the package, and one sensor is located at the left
side. The CJC sensors measure the average temperature at the terminal blocks so that the cold junction
voltage can be calculated. A software algorithm automatically corrects for the additional thermocouples
created at the terminal blocks by subtracting the calculated cold junction voltage from the analog input's
thermocouple voltage measurement.

Increasing the thermocouple length

If you need to increase the length of your thermocouple, use the same type of thermocouple wires to
minimize the error introduced by thermal EMFs.

Data linearization

After the CJC correction is performed on the measurement data, an on-board microcontroller
automatically linearizes the thermocouple measurement data using National Institute of Standards and
Technology (NIST) linearization coefficients for the selected thermocouple type.

The measurement data is then output as a 32-bit floating point value in the configured format (voltage or
temperature).

Open-thermocouple detection (OTD)

The USB-TEMP is equipped with an open-thermocouple detection for each analog input channel. With
OTD, any open-circuit or short-circuit condition at the thermocouple sensor is detected by the software.
An open channel is detected by driving the input voltage to a negative value outside the range of any
thermocouple output. The software recognizes this as an invalid reading and flags the appropriate
channel. The software continues to sample all channels when OTD is detected.

Input leakage current

With open-thermocouple detection enabled, 105 nA (max.) of input leakage current is injected into the
thermocouple. This current can cause an error voltage to develop across the lead resistance of the
thermocouple that is indistinguishable from the thermocouple voltage you are measuring. You can
estimate this error voltage with the following formula:

error voltage = resistance of the thermocouple x 105 nA

4-1

USB-TEMP User's Guide Functional Details

To reduce the error, reduce the length of the thermocouple to lower its resistance, or lower the AWG of
the wire by using a wire with a larger diameter. With open-thermocouple detection disabled, 30 nA (max)
of input leakage current is injected into the thermocouple.

RTD and thermistor measurements

RTDs and thermistors are resistive devices that require an excitation current to produce a voltage drop
that can be measured differentially across the sensor. The USB-TEMP measures the sensor resistance by
forcing a known excitation current through the sensor and then measuring (differentially) the voltage
across the sensor to determine its resistance.

After the voltage measurement is made, the resistance of the RTD is calculated using Ohms law – the
sensor resistance is calculated by dividing the measured voltage by the current excitation level (±
source. The value of the ±

Once the resistance value is calculated, the value is linearized in order to convert it to a temperature
value. The measurement is returned by software as a 32-bit floating point value in a voltage, resistance or
temperature format.

Ix source is stored in local memory.

Data linearization

An on-board microcontroller automatically performs linearization on RTD and thermistor measurements.

! RTD measurements are linearized using a Callendar-Van Dusen coefficients algorithm (you select

DIN, SAMA, or ITS-90).

! Thermistor measurements are linearized using a Steinhart-Hart linearization algorithm (you supply

the coefficients from the sensor manufacturer's data sheet).

Ix)

USB connector

The USB connector provides +5V power and communication. No external power supply is required.

LED

The LED indicates the communication status of the USB-TEMP. It uses up to 5 mA of current. Table 4-2
defines the function of the USB-TEMP LED.

Table 4-2. LED Illumination

LED
Illumination

Steady green The USB-TEMP is connected to a computer or external USB hub.

Pulsing green Data is being transferred.

Indication

Upon connection, the LED should flash three times and then remain lit (indicates a successful
installation).

Power

The two +5V terminals are isolated (500VDC) from the USB +5V.

Caution! Each +5V terminal is an output. Do not connect to an external power supply or you may

damage the USB-TEMP and possibly the computer.

4-2

Specifications

Typical for 25 °C unless otherwise specified.
Specifications in italic text are guaranteed by design.

Analog input section

Table 5-1. Generic analog input specifications

Parameter Conditions Specification

A/D converters Four dual 24-bit, Sigma-Delta type

Number of channels 8 differential

Input isolation

Channel configuration

Differential input voltage
range for the various sensor
categories

Absolute maximum input
voltage

Input impedance 5 Gigohm, min.

Thermocouple ±0.080 V

RTD 0 to 0.5 V

Thermistor 0 to 2 V

Semiconductor sensor 0 to 2.5 V

±C0x through ±C7x relative to GND
(pins 9,19,28,38)

Open thermocouple detect disabled 30 nA max. Input leakage current

500 VDC minimum between field wiring
and USB interface

Software programmable to match sensor
type

±25V power on, ±40 V power off.

Chapter 5

Open thermocouple detect enabled 105 nA max.

Normal mode rejection ratio f

Common mode rejection
Ratio

Resolution 24 bits

No missing codes 24 bits

Input coupling DC

Warm-up time 30 minutes min.

Open thermocouple detect

=60 Hz 90 dB min.

IN

f

IN=50 Hz/60 Hz 100 dB min.

Automatically enabled when the channel
pair is configured for thermocouple sensor.

The maximum open detection time is
3 seconds.

15 °C to 35 °C ±0.25 °C typ.,±0.5 °C max. CJC sensor accuracy

0 °C to 70 °C -1.0 to +0.5 °C max

5-1

USB-TEMP User's Guide Specifications

Channel configurations

Table 5-2. Channel configuration specifications

Sensor Category Conditions Specification

Disabled

Thermocouple 8 differential channels

Semiconductor sensor 8 differential channels

RTD and thermistor

Note 1: Internally, the USB-TEMP has four, dual-channel, fully differential A/Ds providing a

total of eight differential channels. The analog input channels are therefore configured in
four channel pairs with CH0/CH1 sensor inputs, CH2/CH3 sensor inputs, CH4/CH5
sensor inputs, and CH6/CH7 sensor inputs paired together. This "channel-pairing"
requires the analog input channel pairs be configured to monitor the same category of
temperature sensor. Mixing different sensor types of the same category (such as a type J
thermocouple on channel 0 and a type T thermocouple on channel 1) is valid.

Note 2: Channel configuration information is stored in the EEPROM of the isolated

microcontroller by the firmware whenever any item is modified. Modification is
performed by commands issued over USB from an external application, and the
configuration is made non-volatile through the use of the EEPROM.

Note 3: The factory default configuration is Disabled. The Disabled mode will disconnect the

analog inputs from the terminal blocks and internally ground all of the A/D inputs. This
mode also disables each of the current excitation sources.

2-wire input configuration with a single sensor 4 differential channels

2-wire input configuration with two sensors 8 differential channels

3-wire configuration with a single sensor per channel pair 4 differential channels

4-wire input configuration 8 differential channels

Compatible sensors

Table 5-3. Compatible sensor type specifications

Parameter Conditions

Thermocouple

RTD

Thermistor Standard 2,252 ohm through 30,000 ohm

Semiconductor / IC TMP36 or equivalent

J: -210 °C to 1200 °C

K: -270 °C to 1372 °C

R: -50 °C to 1768 °C

S: -50 °C to 1768 °C

T: -270 °C to 400 °C

N: -270 °C to 1300 °C

E: -270 °C to 1000 °C

B: 0 °C to 1820 °C

100 ohm PT (DIN 43760: 0.00385 ohms/ohm/°C)

100 ohm PT (SAMA: 0.003911 ohms/ohm/°C)

100 ohm PT (ITS-90/IEC751:0.0038505 ohms/ohm/°C)

5-2

USB-TEMP User's Guide Specifications

Accuracy

Thermocouple measurement accuracy

Table 5-4. Thermocouple accuracy specifications, including CJC measurement error

Sensor Type Maximum error Typical error Temperature range

J ±0.575 °C ±0.279 °C -210 to 1200 °C

K ±0.629 °C ±0.309 °C -200 to 1372 °C

±1.159 °C ±0.991 °C -50 to 1768.1 °C S

±0.806 °C ±0.634 °C 250 to 1768.1 °C

±1.142 °C ±0.974 °C -50 to 1768.1 °C R

±0.767 °C ±0.619 °C 250 to 1768.1 °C

±1.520 °C ±1.242 °C 250 to 1820 °C B

±0.912 °C ±0.698 °C 700 to 1820 °C

E ±0.553 °C ±0.263 °C -200 to 1000 °C

±0.641 °C ±0.347 °C -200 to 600 °C T

±0.529 °C ±0.281 °C 0 to 600 °C

±0.738 °C ±0.420 °C -200 to 1300 °C N

±0.596 °C ±0.318 °C 0 to 1300 °C

Note 4: Thermocouple measurement accuracy specifications include linearization, cold-junction

compensation and system noise. These specs are for one year, or 3000 operating hours,
whichever comes first, and for operation of the USB-TEMP between 15 °C and 35 °C.
For measurements outside this range, add ±0.5 degree to the maximum error shown.
There are CJC sensors on each side of the module. The accuracy listed above assumes the
screw terminals are at the same temperature as the CJC sensor. Errors shown do not
include inherent thermocouple error. Please contact your thermocouple supplier for
details on the actual thermocouple error.

Note 5: Thermocouples must be connected to the USB-TEMP such that they are floating with

respect to GND (pins 9, 19, 28, 38). The USB-TEMP GND pins are isolated from earth
ground, so connecting thermocouple sensors to voltages referenced to earth ground is
permissible as long as the isolation between the GND pins and earth ground is
maintained.

Note 6: When thermocouples are attached to conductive surfaces, the voltage differential between

multiple thermocouples must remain within ±1.4V. For best results we recommend the
use of insulated or ungrounded thermocouples when possible.

Semiconductor sensor measurement accuracy

Table 5-5. Semiconductor sensor accuracy specifications

Sensor Type

TMP36 or equivalent

Note 7: Error shown does not include errors of the sensor itself. These specs are for one year

while operation of the USB-TEMP unit is between 15 °C and 35 °C. Please contact your
sensor supplier for details on the actual sensor error limitations.

Temperature Range (

-40 to 150

°C)

Maximum Accuracy Error

°C ±0.50 °C

5-3

USB-TEMP User's Guide Specifications

RTD measurement accuracy

Table 5-6. RTD measurement accuracy specifications

RTD Sensor

Temperature

PT100, DIN, US or
ITS-90

Note 8: Error shown does not include errors of the sensor itself. The sensor linearization is

-200 °C ±0.15 ±0.08

-0 °C ±0.18 ±0.11

100 °C ±0.26 ±0.15

300 °C ±0.37 ±0.23

600 °C ±0.43 ±0.27

Maximum Accuracy Error (°C)
Ix+ = 210 µA

Typical Accuracy Error (°C)
Ix+ = 210 µA

performed using a Callendar-Van Dusen linearization algorithm. These specs are for one
year while operation of the USB-TEMP unit is between 15 °C and 35 °C. The
specification does not include lead resistance errors for 2-wire RTD connections. Please
contact your sensor supplier for details on the actual sensor error limitations.

Note 9: Resistance values greater than 660 ohms cannot be measured by the USB-TEMP in the

RTD mode. The 660 ohm resistance limit includes the total resistance across the current
excitation (±Ix) pins, which is the sum of the RTD resistance and the lead resistances.

Note 10: For accurate three wire compensation, the individual lead resistances connected to the ±Ix

pins must be of equal value.

Thermistor measurement accuracy

Table 5-7. Thermistor measurement accuracy specifications

Thermistor Temperature Range Maximum Accuracy Error (°C)

Ix+ = 10 µA

2252 Ω -40 to120 °C ±0.05

3000 Ω -40 to120 °C ±0.05

5000 Ω -35 to120 °C ±0.05

10000 Ω -25 to120 °C ±0.05

30000 Ω -10 to120 °C ±0.05

Note 11: Error shown does not include errors of the sensor itself. The sensor linearization is

performed using a Steinhart-Hart linearization algorithm. These specs are for one year
while operation of the USB-TEMP unit is between 15°C and 35°C. The specification does
not include lead resistance errors for 2-wire thermistor connections. Please contact your
sensor supplier for details on the actual sensor error limitations. Total thermistor
resistance on any given channel pair must not exceed 180k ohms. Typical resistance
values at various temperatures for supported thermistors are shown in Table 5-8.

5-4

USB-TEMP User's Guide Specifications

Table 5-8. Typical thermistor resistance specifications

Temp 2252 Ω

thermistor

-40 °C 76 kΩ 101 kΩ 168 kΩ 240 kΩ (Note 12) 885 kΩ (Note 12)

-35 °C 55 kΩ 73 kΩ 121 kΩ 179 kΩ 649 kΩ (Note 12)

-30 °C 40 kΩ 53 kΩ 88 kΩ 135 kΩ 481 kΩ (Note 12)

-25 °C 29 kΩ 39 kΩ 65 kΩ 103 kΩ 360 kΩ (Note 12)

-20 °C 22 kΩ 29 kΩ 49 kΩ 79 kΩ 271 kΩ (Note 12)

-15 °C 16 kΩ 22 kΩ 36 kΩ 61 kΩ 206 kΩ (Note 12)

-10 °C 12 kΩ 17 kΩ 28 kΩ 48 kΩ 158 kΩ

-5 °C 9.5 kΩ 13 kΩ 21 kΩ 37 kΩ 122 kΩ

0 °C 7.4 kΩ 9.8 kΩ 16 kΩ 29 kΩ 95 kΩ

Note 12: Resistance values greater than 180k ohms cannot be measured by the USB-TEMP in the

3000 Ω
thermistor

5 kΩ
thermistor

10 kΩ
thermistor

30 kΩ
thermistor

thermistor mode. The 180k ohm resistance limit includes the total resistance across the
current excitation (±Ix) pins, which is the sum of the thermistor resistance and the lead
resistances.

Note 13: For accurate three wire compensation, the individual lead resistances connected to the ±Ix

pins must be of equal value.

Throughput rate

Table 5-9. Throughput rate specifications

Number of Input Channels Maximum Throughput

1 2 Samples/second

2 2 S/s on each channel, 4 S/s total

3 2 S/s on each channel, 6 S/s total

4 2 S/s on each channel, 8 S/s total

5 2 S/s on each channel, 10 S/s total

6 2 S/s on each channel, 12 S/s total

7 2 S/s on each channel, 14 S/s total

8 2 S/s on each channel, 16 S/s total

Note 14: The analog inputs are configured to run continuously. Each channel is sampled twice per

second. The maximum latency between when a sample is acquired and the temperature
data is provided by the USB unit is approximately 0.5 seconds.

5-5

USB-TEMP User's Guide Specifications

Digital input/output

Table 5-10. Digital input/output specifications

Digital type CMOS

Number of I/O 8 (DIO0 through DIO7)

Configuration Independently configured for input or output.

Power on reset is input mode.

Pull up/pull-down configuration

Digital I/O transfer rate
(software paced)

Input high voltage 2.0 V min., 5.5 V absolute max.

Input low voltage 0.8 V max., -0.5 V absolute min.

Output low voltage (IOL = 2.5 mA) 0.7 V max

Output high voltage (IOH = -2.5 mA) 3.8 V min.

Note 15: All ground pins on the USB-TEMP (pins 9, 19, 28, 38) are common and are isolated from

earth ground. If a connection is made to earth ground when using digital I/O and
conductive thermocouples, the thermocouples are no longer isolated. In this case,
thermocouples must not be connected to any conductive surfaces that may be referenced
to earth ground.

All pins pulled up to +5 V via 47 K resistors (default). Pull down to
ground (GND) also available.

! Digital input – 50 port reads or single bit reads per second typ.
! Digital output – 100 port writes or single bit writes per second typ.

Memory

Table 5-11. Memory specifications

EEPROM 1,024 bytes isolated micro reserved for sensor configuration

256 bytes USB micro for external application use

Microcontroller

Table 5-12. Microcontroller specifications

Type Two high performance 8-bit RISC microcontrollers

USB +5V voltage

Table 5-13. USB +5V voltage specifications

Parameter Conditions Specification

USB +5V (VBUS) input voltage range 4.75 V min. to 5.25 V max.

5-6

USB-TEMP User's Guide Specifications

Power

Table 5-14. Power specifications

Parameter Conditions Specification

Supply current USB enumeration <100 mA

Supply current
(Note 16)

User +5V output voltage range
(terminal block pin 21 and pin 47)

User +5V output current
(terminal block pin 21 and pin 47)

Isolation Measurement system to PC 500 VDC min.

Note 16: This is the total current requirement for the USB-TEMP which includes up to 10 mA for

the status LED.

Note 17: Self-Powered Hub refers to a USB hub with an external power supply. Self-powered hubs

allow a connected USB device to draw up to 500 mA.

Root Port Hubs reside in the PC’s USB Host Controller. The USB port(s) on your PC are
root port hubs. All externally powered root port hubs (desktop PC’s) provide up to
500 mA of current for a USB device. Battery-powered root port hubs provide 100 mA or
500 mA, depending upon the manufacturer. A laptop PC that is not connected to an
external power adapter is an example of a battery-powered root port hub.

Continuous mode 70 mA max.

Connected to self-powered hub. (Note 17) 4.75 V min. to

5.25 V max.

Bus-powered and connected to a self-powered hub.
(Note 17)

10 mA max.

USB specifications

Table 5-15. USB specifications

USB device type USB 2.0 (full-speed)

Device
compatibility

Self-powered, 100 mA consumption max

USB cable type

USB cable length 3 meters max.

USB 1.1, USB 2.0

A-B cable, UL type AWM 2527 or equivalent. (min 24 AWG VBUS/GND, min 28 AWG
D+/D-)

Current excitation outputs (Ix+)

Table 5-16. Current excitation output specifications

Parameter Conditions Specification

Configuration 4 dedicated pairs:

±I1 - CH0/CH1
±I2 - CH2/CH3
±I3 - CH4/CH5
±I4 - CH6/CH7

Thermistor 10 µA typ. Current excitation output ranges

RTD 210 µA typ.

Tolerance ±5% typ.

Drift 200 ppm/°C

Line regulation 2.1 ppm/V max.

Load regulation 0.3 ppm/V typ.

Output compliance voltage (relative to GND pins 9,19,28,38) 3.90 V max.

-0.03 V min.

5-7

USB-TEMP User's Guide Specifications

Note 18: The USB-TEMP has four current excitation outputs, with ±I1 dedicated to the CH0/CH1

analog inputs, ±I2 dedicated to CH2/CH3, ±I3 dedicated to CH4/CH5, and ±I4 dedicated
to CH6/CH7. The excitation output currents should always be used in this dedicated
configuration.

Note 19: The current excitation outputs are automatically configured based on the sensor

(thermistor or RTD) selected.

Environmental

Table 5-17. Environmental specifications

Operating temperature range 0 to 70 ° C
Storage temperature range -40 to 85 ° C
Humidity 0 to 90% non-condensing

Mechanical

Table 5-18. Mechanical specifications

Dimensions 127 mm (L) x 88.9 mm (W) x 35.56 (H)

User connection length 3 meters max.

Screw terminal connector type and pin out

Table 5-19. Screw terminal connector specifications

Connector type Screw terminal

Wire gauge range 16 AWG to 30 AWG

5-8

USB-TEMP User's Guide Specifications

Screw terminal pin out

Table 5-20. Screw terminal pin out

Pin Signal

Name

1 I1+ CH0/CH1 current excitation source 27 I4- CH6/CH7 current excitation return
2 NC 28 GND
3 C0H CH0 sensor input (+) 29 C7L

4 C0L

5 4W01 CH0/CH1 4-wire, 2 sensor common 31 IC67 CH6/CH7 2 sensor common
6 IC01 CH0/CH1 2-sensor common 32 4W67 CH6/CH7 4-wire, 2 sensor common
7 C1H CH1 sensor input (+) 33 C6L

8 C1L

9 GND 35 NC
10 I1- CH0/CH1 current excitation return 36 I4+ CH6/CH7 current excitation source

CJC sensor

11 I2+ CH2/CH3 current excitation source 37 I3- CH4/CH5 current excitation return
12 NC 38 GND
13 C2H CH2 sensor input (+) 39 C5L

14 C2L

15 4W23 CH2/CH3 4-wire, 2 sensor common 41 IC45 CH4/CH5 2 sensor common
16 IC23 CH2/CH3 2 sensor common 42 4W45 CH4/CH5 4-wire, 2 sensor common
17 C3H CH3 sensor input (+) 43 C4L

18 C3L

19 GND 45 NC
20 I2- CH2/CH3 current excitation return 46 I3+ CH4/CH5 current excitation source
21 +5V +5V output 47 +5V +5V output
22 GND 48 GND
23 DIO0 Digital Input/Output 49 DIO7 Digital Input/Output
24 DIO1 Digital Input/Output 50 DIO6 Digital Input/Output
25 DIO2 Digital Input/Output 51 DIO5 Digital Input/Output
26 DIO3 Digital Input/Output 52 DIO4 Digital Input/Output

Pin Description Pin Signal

CH0 sensor input (

CH1 sensor input (

CH2 sensor input (

CH3 sensor input (

-)

-)

-)

-)

Name

30 C7H CH7 sensor input (+)

34 C6H CH6 sensor input (+)

CJC sensor

40 C5H CH5 sensor input (+)

44 C4H CH4 sensor input (+)

Pin Description

CH7 sensor input (

CH6 sensor input (

CH5 sensor input (

CH4 sensor input (

-)

-)

-)

-)

5-9

Measurement Computing Corporation

16 Commerce Boulevard,

Middleboro, Massachusetts 02346

[phone]

Fax: [phone]

E-mail: [e-mail]

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